An individual communicates with other people in a variety of business and social networks, often using a variety of electronic protocols and services such as e-mail, instant messaging (IM), text messaging and the like. An individual user may maintain an address book for each communication system (for example, e-mail service); the address book reflects the user's network of contacts over that system. Address books do not travel across mail systems; that is, it is generally necessary for a user to maintain a separate address book for each communication service. Moreover, address books by themselves do not include useful information about the relationships of the user with other people in the network.